Certain powder bulk materials, such as certain rare earths and silica gel are difficult to handle because of their tendency to clump or clod when compacted. If shipped in a closed large volume container, such as a tank car or trailer, this type of material is subject to settling and clumping due to the normal shocks and movement it receives during transport. As such, such material may not be easily removed from such a container.
While various trailers and containers have in the past tried difficult unloading schemes, these have heretofore failed to provide an easy and economical manner of unloading bulk shipped powder materials of this type. Such prior unloading systems include those shown in the following U.S. Pat. Nos. 4,247,228; 2,494,500; 3,251,497; 4,993,883; 4,900,200; 4,875,811; 4,842,449; 4,449,861; 3,917,354; and 3,265,232. Some of these prior art approaches involve aspiration of the product by injecting air under pressure into a closed container at the exit from the container and extracting the product entrained with air. While that approach may work well with some types of products, if applied to clodding powder bulk materials, it would have the drawback of fluidizing and removing product only at the area of the exits and of producing an output that was largely air. This latter drawback would require provision for screening out or settling out of the powder after it was discharged from the container.
The present invention provides a system for unloading such bulk material which does not involve removing the material mixed with a large volume of air and which also allows for the removal and fluidizing of substantially all of the material during unloading so that substantially all of the bulk material may be automatically unloaded with little or no need of direct human labor in handling the material.